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British Standards for CO Alarms Explained


The existence of more than one British Standard in relation to the manufacture of carbon monoxide alarms has long been a source of confusion for people trying to compare different models before making a purchase. This uncertainty can make it more difficult to tell which CO detector would be most suitable for your needs unless you understand the distinction between the various standards.

Before exploring the differences between the guiding standards, it is important to note that all CO detectors offered by Safelincs are CE approved and kitemarked to the appropriate version of the British Standard. We continuously monitor the quality and conformity of every single product we sell. This ensures our customers can choose with absolute confidence from all of the CO detectors we offer, knowing that they conform to all relevant manufacturing standards.

The Manufacturing Standards

The manufacturing standard covering carbon monoxide detectors is divided into two parts. The previous guiding standard BS 50291:2001 was superceded in April 2011 and a decision was made to split the standard into two parts, with part one covering domestic grade CO detectors, and part two covering detectors intended for use in recreational vehicles such as caravans or boats.

The majority of CO detectors bought are purchased for use within a standard domestic setting, and are intended to be stationary throughout their lifespan. Of course the home is not the only place where there is a risk of carbon monoxide poisoning, therefore there is also a range of 'portable' devices that are tested further to ensure they can withstand the conditions likely to be encountered if the product is used in a recreational vehicle.

The additional testing allows manufacturers to mark certain CO alarms as being suitable for vehicles. This distinction is a handy indicator for those in the know, but has been known to cause uncertainty for some people when browsing for a new carbon monoxide detector. To help alleviate any confusion, we have summarised each part of the standard below.

Part 1:

BS EN 50291-1:2018 Summary:
Title: Electrical apparatus for the detection of carbon monoxide in domestic premises. Test methods and performance requirements. Published: May 2018
Replaced: BS 50291:2010
Look for this if: Purchasing a CO alarm for home use

This part one defines the test methods and performance requirements for 'electrical apparatus for the detection of carbon monoxide in domestic premises', i.e. carbon monoxide detectors. It covers a wide range of performance and durability measures, and lays out the means, and extent of testing for things such as sensor reaction times, temperature resistance and minimum alarm volume levels.

This is the most widely applicable testing standard for carbon monoxide detectors, and is intended to set a base performance level for devices sold 'for continuous operation in domestic premises'.

You should ensure that a CO detector purchased for the home conforms to either part one or part two of BS EN 50291.

Part 2:

BS EN 50291-2:2019 Summary:
Title: Electrical apparatus for the detection of carbon monoxide in domestic premises. Electrical apparatus for continuous operation in a fixed installation in recreational vehicles and similar premises including recreational craft. Additional test methods and performance requirements. Published: September 2019
Replaced: BS EN 50291-2:2010
Look for this if: Purchasing a CO alarm for a vehicle (or home)

This part two defines the additional testing needed, and the expected performance criteria for carbon monoxide detectors which are likely to be subject to movement or vibration during their lifespan. In general terms it can be considered that alarms conforming to this standard are more robust than alarms simply carrying the part one kitemark.

This testing standard is becoming a more common sight, perhaps as a result of a growing appetite for portable CO detectors. Recent public information campaigns have valiantly attempted to raise awareness of the dangers of carbon monoxide when camping or boating for example.

Holidaymakers or regular boat and caravan users now have a way of discerning at a glance which CO detectors are designed specifically to keep them safe when travelling. You should always ensure that any CO detectors purchased for use outside of a standard domestic setting conform to part two of BS EN 50291.

The Installation and Maintenance Standard

As well as the standards mapping out the required quality and performance levels of alarms for manufacturing purposes, there is also a standard which defines best practice in terms of installation and maintenance.

BS EN 50292:2013 Summary:
Title: Electrical apparatus for the detection of carbon monoxide in domestic premises, caravans and boats. Guide on the selection, installation, use and maintenance. Published: November 2013
Replaced: BS 50292:2002
Look for this if: Professionally installing alarms

This British standard is the 'Guide on the selection, installation, use and maintenance' of 'Electrical apparatus for the detection of carbon monoxide in domestic premises, caravans and boats'. A simple memory tool to help appreciate the difference between this standard and those previously mentioned would be; carbon monoxide detectors cannot be manufactured to BS EN 50292:2013, but they should be installed to BS EN 50292:2013.

Luckily, to simplify matters for those purchasing CO alarms, the two standards are intertwined. In order to earn a kitemark for either part one or part two of BS EN 50291, the alarm's instructions must be in accordance with BS EN 50292:2013.

For professional installers of carbon monoxide detectors, a working knowledge of BS EN 50292:2013 is essential. However, for non-commercial installers simply following the installation instructions provided should ensure your alarms are sited in accordance to this standard.

Further Information

We hope this information has helped define the differences between each standard, and will remove any potential confusion for those purchasing a carbon monoxide detector.

To summarise, all of the CO detectors Safelincs offer meet at least BS EN 50291-1:2010+A1:2012, and as a result include instructions in accordance with BS EN 50292:2013. Therefore you can have complete confidence in your purchase when you buy from Safelincs.

For further information about the dangers of CO, visit

If you would like more information about the carbon monoxide detectors and the related products we sell, feel free to browse our dedicated CO detector section, or contact us via or on 0800 612 6537.


Reviewed: 15/02/2022 (doc:51 V1.2). Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. Please note that we provide abridged, easy-to-understand guidance. To make detailed decisions about your fire safety provisions, you might require further advice or need to consult the full standards and legislation.


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